In the midst of celebrating recent Hubble Space Telescope (HST)
results, we invite you to pause and reflect on the conditions, forces,
and processes that gave rise to this magnificent research facility.
For unlike the principles of nature, those factors are not immutable
but are changing. When we consider what space observatories should
follow HST, we must consider not only scientific needs and technical
opportunities but also broadened concepts about the role of science
in society, current fiscal constraints, and emerging public policies.
Achieving this synoptic perspective has been the primary challenge
to recent study activities in the United States pertaining to space
astronomy following the prime mission of the HST in 2005.

Also, while in Paris celebrating the internationality of the HST
Program, we invited our European colleagues to recognize certain
differences in the processes of science funding in the United States as
compared with other spacefaring countries. Among these differences are
annual space budget debates in the United States Congress, compared
with the long-term treaty commitments of the European Space Agency.
We might also point out the 200-year debate in the United States about
the benefits and desirability of publicly sponsored research, compared
with an historical and cultural commitment to science in Europe. It is
hard for most astronomers in the United States to recall a time when
there was essentially no public funding of astronomical exploration,
yet prior to 50 years ago that was the situation in our country.

In 1946, Lyman Spitzer first advocated a telescope in space to explore
the cosmos with unprecedented clarity and spectral coverage. The chief
contribution of such a radically new and more powerful instrument, he
wrote, ``would be, not to supplement our present ideas of the universe
we live in, but rather to uncover new phenomena not yet imagined, and
perhaps to modify profoundly our basic concepts of space and time.''
One year before, Vannevar Bush, who led the wartime science effort
in the United States, published what would become the charter of
American science for the Cold War years, a monograph called ``Science,
the Endless Frontier.'' It invoked the resonant myth of the American
West, and provided a rationale for science funding in peacetime based on
serendipitous benefits that historically have accrued from exploration,
such as stimulus to education and discoveries leading to new products and
processes for the marketplace. Bush's frontier metaphor was embraced by
policy makers, with two important consequences: unprecedented investment
in ground-based astronomical observatories and the advent of a cadre of
skilled astronomers supported by the federal government to use these
facilities for research. These commitments notwithstanding, the decision
in the 1970s to build HST required an additional basis, for the concept of
science for its own sake could not alone support such an investment---most
of a million dollar outlay for every professional astronomer in the
country. Fortunately, the Space Shuttle was a transportation vehicle
needing an exciting science payload to demonstrate the utility of humans
in space, and HST became the prized solution.

Today, while enjoying the success of HST, we all must recognize that the
environment of the space and science programs in the United States has
changed significantly from the conditions that created the astronomical
facilities and professional circumstances of today. There is no longer a
blind faith that federal funds for basic scientific research will produce
more accomplished schoolchildren, assure competitiveness in global markets
or otherwise ameliorate America's problems. Indeed, decision makers appear
to have rejected `the endless frontier' as a useful public policy concept.
Thus, the search is underway for some consensus rationale to continue
funding space astronomy at levels comparable to the present.

The HST & Beyond Study, conducted by the Association of Universities
for Research in Astronomy (AURA) with support from NASA, suggests such
a qualitatively new rationale for public funding of space astronomy.
What that rationale is, and the type of research program it calls for,
is the subject of the remainder of this paper.

The charter of the study reads, ``The HST & Beyond Committee is charged
to study possible missions and programs for optical-ultraviolet astronomy
in space for the first decades of the 21st century. It should initiate
a process which will produce a new consensus vision of the long term
goals of this scientific enterprise.''

The membership of the HST & Beyond Committee is:

Alan Dressler, Chair (Carnegie Observatories)

Robert A. Brown (Space Telescope Science Institute)

Arthur F. Davidsen (Johns Hopkins University)

Richard S. Ellis (Cambridge University)

Wendy L. Freedman (Carnegie Observatories)

Richard F. Green (National Optical Astronomical Observatories)

Michael Hauser (Space Telescope Science Institute)

Robert P. Kirshner (Harvard University)

Shrinivas Kulkarni (California Institute of Technology)

Simon Lilly (University of Toronto)

Bruce H. Margon (University of Washington)

Carolyn C. Porco (University of Arizona)

Douglas O. Richstone (University of Michigan)

H. S. (Peter) Stockman (Space Telescope Science Institute)

Harley A. Thronson, Jr. (University of Wyoming)

John L. Tonry (Massachusetts Institute of Technology)

James Truran (University of Chicago)

Edward J. Weiler (NASA/Headquarters, ex officio)

The Committee met three (and one-half) times, in April 1994, September 1994,
and May 1995, and then briefly in conjunction with the January 1995 meeting
of the American Astronomical Society, where we opened the process to the
community by inviting their comments on, and participation in, our debate
and deliberations.

The Committee developed a variety of candidate astronomical themes that
could define the space observatories to succeed HST. They elaborated
these themes in terms of research issues, measurement requirements, and
intellectual ramifications. We heard presentations about new technical
capabilities such as adaptive optics, interferometry, and advanced
mirror technology.

We also philosophized at length about the exact nature of our apparent
opportunity to inform our community and influence the political
environment regarding the future of space astronomy in the United States.

Finally, we assessed the themes---and the missions and programs to
pursue them---according to scientific merit, technological readiness,
and a non-scientific criterion: How will the taxpayer benefit from this
astronomical research? A study asking that question is not entirely new.
To its credit, the last Astronomy Survey Committee (Bahcall Committee)
asked the same question for their 1990 report. They recognized that the
benefits of space astronomy accrue to the human mind, as telescopes
gather neither gold nor jewels except as people experience them in
thought. To pursue those benefits, the Bahcall Committee recommended
``an education initiative in astronomy,'' which should feed the public's
fascination with exotic discoveries and serve as a handmaiden to basic
teaching and training of new scientists. Today, the national astronomy
program is wrestling with the implications of this recommendation in
terms of approaches and measurable outcomes.

The HST & Beyond Committee goes further than the Bahcall Committee,
proposing to seize upon another educational opportunity uniquely
accessible through astronomy: to address ancient questions about
the origins of our cosmos, our world, and the life it contains.
This new departure has to do with informing perspective and world view.
Its distinctive quality is perhaps best appreciated by reflecting on
the changes in the human mind inspired by Nicolaus Copernicus almost
500 years ago.

The Copernican revolution was not one but two revolutions. The first,
the one with which scientists are most familiar, placed the Earth in its
proper place in the skies, orbiting the Sun, not the other way around.
This masterstroke inspired science as we know it. The scientific method
itself was formulated in the process of sorting out where the planets
are in three-dimensional space. Important tools, such as the calculus,
were devised to assist the inquiry.

The second Copernican `revolution' affected vastly more people, for it
impinged upon their world view. If the Earth was just another planet,
then the human experience of Earth might or might not distinguish
it from other worlds like it. What happened here on Earth might have
happened in all those myriad `theres'. This ramification of science,
this second revolution, has played itself out in nearly 500 years of
robust philosophical debate about the uniqueness of Earth. Today, for
the first time in human history, we can describe, design, and build the
telescope---the interferometer---to discover other worlds orbiting nearby
stars and measure their properties, including whether these worlds may
be habitable.

The wider question of our cosmic place in time and space is another
important extension of the Copernican revolutions. It is also a question
that just in our time has become accessible with telescopes in space.
We can describe, design, and build a telescope to look back in time to
the earliest galaxies like our Milky Way, and follow the progression of
events that gave rise to our galactic home.

HST has set the stage for this scientific opportunity with proof of
the evolution of galaxies back as far as light in the visible spectrum
can inform us, and with evidence of disks where planets may be building
around young stars. These results encourage us to believe that some day
we will be able to describe and understand in detail the cosmic events
that led to the conditions suitable to our own existence.

Toward this end, and in line with the broader general discussion of
the candidate astronomical themes, the HST & Beyond Committee has
identified two major scientific goals, whose accomplishment will justify
a commitment well into the next century: (1) the direct study of the
birth and evolution of normal galaxies such as the Milky Way, and (2)
the detection of Earth-like planets around other stars and the search
for the evidence of life on them. Despite substantial progress in both
areas in recent years, we have not achieved, nor have we at present the
means to achieve, these two ambitious and crucial goals.

To further these two central scientific endeavors, and to simultaneously
provide the broad capabilities of ultraviolet-optical-infrared astronomy
in space that are necessary to advance the field on its many fronts,
the HST & Beyond Committee recommends the following program:

(1) The HST should be operated beyond its currently scheduled termination
date of 2005. An emphasis on ultraviolet imaging and spectroscopy,
and wide-field, high-resolution optical-light imaging makes the HST a
critical astronomical tool through the first decade of the next century.
Present budgeting shows that this premier scientific tool could be
operated in a ``no repair, no upgrade'' mode at approximately 20% of
its present operation and maintenance cost, which would allow a highly
cost-effective return on the investment in HST beyond 2005.

(2) NASA should develop a space observatory of aperture 4 m or larger,
optimized for operation over the wavelength range 1--5 microns with
imaging and spectroscopy. Extension of capabilities shortward to about
0.5 micron and longward to at least a 20 micron would greatly increase
the observatory's versatility and productivity. The Committee strongly
recommends this course, if it can be done without a substantial
increase in cost. Such an observatory should be the first major
astronomical ``facility class'' instrument in space to follow the
AXAF and SIRTF programs. It will be an essential tool in an ambitious
program of study in all areas of astronomy, especially in the origin
and evolution of galaxies. The technology necessary for a cost-effective
facility-class mission at these wavelengths---including ultra-lightweight
precision mirrors and structures, advanced cooling systems, and ``smart''
controls---will be important for a variety of concurrent and follow-on
programs, such as the imaging interferometry program discussed below.
We believe that an approximate cost of $500 million for a 4-m version
of this facility is a realistic and desirable goal.

(3) NASA should develop the capability for space interferometry. This will
lead to a mission for astrometric observations in visible light at the
10 microarcseconds or better level, and the eventual construction of an
imaging interferometer. The Committee recognizes this technology as a
vital next step in pursuit of fundamental astrophysical questions and,
specifically, sees IR interferometry from space as essential to one of
our primary goals: the detection and study of Earth-like planets around
neighboring stars.

Accomplishing these ambitious goals within the resources that are likely
to be available in future years will require new space technologies
hardware and innovations in the management of large projects, activities
that are already advancing within NASA. International cooperation will
be needed. By increasing their direct involvement in the building and
operation of these facilities, astronomers can take a positive, active
role in achieving these objectives.

Because the lead time for such challenging missions is long, two
different kinds of activities must begin soon. First, the HST & Beyond
Committee recommends that NASA set up study teams to investigate the
technical issues involved in building and economical, large-aperture,
near-IR-optimized space telescope. This effort will support and parallel
the activities already underway within NASA to explore the possibilities
for space interferometry. Improved information regarding capabilities,
costs, and tradeoffs will be crucial to the deliberations of the next
decennial survey report in astronomy and astrophysics.

The HST & Beyond Committee also recognizes that it is increasingly
important for scientists to explain their motivations, goals, and
results to the society that supports their research. The necessity of
doing so is especially acute because, as we draw nearer to answering
some of humanity's ancient questions, it would appear that competition
for the resources available for scientific research will be stronger
than at any time in the last half century.

It is not often given to science that it can inform directly a culture's
attitudes and beliefs and an average person's self-understanding.
The Apollo missions to the Moon were terrific scientific and technical
accomplishments, yet their primary impact was beyond traditional science.
That impact, epitomized in the magnificient pictures of the Earth
as an island of life in space, was the realization that our common
inheritance and destiny supersedes the divisions and distinctions between
the people of the world. Darwin's voyage on the Beagle, which led to
the theory of evolution, is another example. Such opportunities are
sufficiently rare, and have been controversial enough, that they must
be taken on with circumspection, for it would be inappropriate for a
government to attempt the task of informing people what they should or
should not believe about their origins and place in the universe in a
religious sense. Nevertheless, not to enquire of nature---not to look at
the evolution of galaxies and not to look for Earth-like planets around
other stars---would be a perilous choice for people committed to truth,
and for a society as committed to objective thinking and technological
progress as is the United States of America. The design of our government
was a singular product of the Enlightenment, which sought to establish the
principle that all human endeavours can and should be informed by science.
Today, the same democratic institutions that arose from that principle
can decide whether or not to shed the light of reason on human origins
in a cosmic context.